All the so-so comments about the S&S strobes certainly mirror all I have read. I wouldn’t buy them.
I had Inon Z240s for years and thought them terrific. But Retra, yep…. Top class! Expensive, yes, but I think worth the cost.
It’s a really good question. My experience with camera/housing for D100/D200/D300 and D800 has been about 30% if I’m lucky of purchase price aer about 3 years if the system was perhaps not more than 2 generations.
That said, I’ve just sold a whole bunch of Nikon lenses and a D5. The lenses ranged from 30% to 80% (the latter for a 300mmFR and a 24mmPC). I’d be embarrassed to say how much I got for a Nikon D5 in pristine condition. I was genuinely horrified. I think I’d be almost suggesting get rid of non-mirrorless fast!
Pretty much as long as you like, Doc. What you don’t use immediately is easily just coiled up by your strobe assistant. Pick a length… 3 feet, 4 feet…. Much depends on the lens and subject and whether yiu want the assistant in the pic too!
I have a ULCS arm loaded with Stix floats horizontally across my housing. My dive computer straps on to that. It's very easy to read by just glancing up. And then if I'm diving without a camera - very rare! - I can just unbuckle the computer and wear it on my wrist.
Sorry, traveling for work so can't post a photo.